Juglans californica

Juglans californica, the California black walnut, also called the California walnut, or the Southern California black walnut,[1] is a large shrub or small tree (about 20–49 feet (6.1–14.9 m)[3]) of the walnut family, Juglandaceae, endemic to the Central Valley and the Coast Range valleys from Northern to Southern California.

Juglans californica
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Juglandaceae
Genus: Juglans
Section: Juglans sect. Rhysocaryon
Species:
J. californica
Binomial name
Juglans californica
Natural range

Distribution

Juglans californica is generally found in the valleys and adjacent slopes of the California Coast Ranges, Transverse Ranges, and Peninsular Ranges. It grows as part of mixed woodlands, and also on slopes and in valleys wherever conditions are favorable. It is threatened by development and overgrazing.[1] Some native stands remain in urban Los Angeles in the Santa Monica Mountains, Hollywood Hills, and Repetto Hills. J. californica grows in riparian woodlands, either in single species stands or mixed with California's oaks (Quercus spp.) and cottonwoods (Populus fremontii).

Description

Juglans californica can be either a large shrub with 1–5 trunks, or a small, single-trunked tree. The main trunk can fork close to the ground, making it look like two trees that have grown together, then diverged. It has thick bark, deeply channeled or furrowed at maturity. It has large, pinnately compound leaves with 11–19 lanceolate leaflets with toothed margins and no hair in the vein angles.[4] It has a small hard nut in a shallowly grooved, thick shell that is difficult to remove.

Uses

Food

The nuts are edible[5] and are eaten by the Chumash Indians of the Channel Islands of California and Ventura County as well as by the Tongva of Los Angeles County. They are not grown commercially as food.

Cultivation

Juglans californica is cultivated throughout California to support the walnut industry, used as a rootstock in English walnut orchards. It is also cultivated as an ornamental tree where it is planted in California native plant, xeriscape, and wildlife habitat gardens and natural landscaping in California, and in Hawaii.

Taxonomy

Some authorities (e.g. the California Native Plant Society) combine this species with Juglans hindsii. On the other hand, a 2007 molecular analysis of the genus[6] suggests J. californica is sister to the remaining black walnuts (section Rhysocaryon). This article follows the conventions of The Jepson Manual.[7][8]

References
  1. Stritch, L.; Barstow, M. (2019). "Juglans californica". IUCN Red List of Threatened Species. 2019: e.T35154A61524825. doi:10.2305/IUCN.UK.2019-2.RLTS.T35154A61524825.en. Retrieved 19 November 2021.
  2. Essa, Lora. "Index of Species Information". U.S. Department of Agriculture, Forest Service. Retrieved April 10, 2013.
  3. "California Black Walnut Trees | City of Walnut, CA". www.cityofwalnut.org. Retrieved 2019-10-17.
  4. Kershner, Mathews, Nelson, and Spellenberg, National Wildlife Federation field Guide to Trees of North America, 2008, Chanticleer Press, Inc. p. 229
  5. Elias, Thomas S.; Dykeman, Peter A. (2009) [1982]. Edible Wild Plants: A North American Field Guide to Over 200 Natural Foods. New York: Sterling. p. 247. ISBN 978-1-4027-6715-9. OCLC 244766414.
  6. Aradhya, M. K, D. Potter, F. Gao, & C. J. Simon: "Molecular phylogeny of Juglans (Juglandaceae): a biogeographic perspective: Tree Genetics & Genomes (2007)3:363–378
  7. Juglans californica S. Watson var. hindsii Jeps.
  8. Juglans hindsii Jeps. ex R. E. Sm.

Further reading
  • Anderson, E. N. "Some preliminary observations on the California black walnut (Juglans californica)" in Fremontia: A Journal of the California Native Plant Society. January 2002.
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